Wrapper for wound filamentary packages



United States Patent a is.

WRAPPER FOR WOUND FILAlVIENTARY PACKAGES Orlando A. Battista, Drexel Hill, and Graeme G. Whytlaw, Swarthmore, Pa., assignors to American Viscose Corporation, Philadelphia, Pa., a corporation of Deiaware No Drawing. Application April 28, 1954 Serial No. 426,298

16 Claims. (Cl. 20664) This invention relates to a method of handling annular packages of filamentary material, and to novel permeable and shrinkable wrappers for the packages comprising paper or paper-like material of such thinness and flexibility as to be conformed readily to both the inner and outer peripheries of the package.

In the manufacture of certain filamentary materials, for example, regenerated cellulose filamentary material from viscose, it is common practice to collect the filaments in the form of a package, provide the package with a wrapper, subject the wrapped package to liquid treatments including washing, and then dry the wrapped package.

Various types of wrappers, including paper Wrappers, have been proposed for use in protecting annular packages of filamentary material during liquid'treatment. Regenerated cellulose filamentary material, which is in highly swollen or gel condition as it is obtained and prior to initial drying, shrinks during the drying step, with shrinkage of the thread package as a whole, and as a consequence, if the wrapper does not shrink with the package during drying, an air pocket is developed between the package and wrapper, which has the effect of decreasing the drying rate. Also, the Wrapper does not fit the dried shrunk package snugly and tends to slip on the package when it is handled, giving rise to dis placement of the windings and damage to the threads during handling and shipping of the dried, wrapped package.

An object of this invention is to provide a novel paper or paper-like wrapper which is characterized by high wet strength and porosity, and which shrinks with the wrapped package during drying, after liquid treatment thereof. Another object is to provide a wrapper adapted to shrink at all areas thereof, in situ on an annular package of filamentary material, the shrinkage at predetermined areas of the wrapper being more pronounced than at other areas, so that strong shrinkage at the scattered areas does not rupture the wrapper.

These objects are accomplished by the present invention in accordance with which a cellulosic material which may be either viscose or an alkali-soluble, water-insoluble cellulose ether, is deposited in the form of spaced, parallel stripes on a surface of a tissue paper having a minimum wet strength of 300 grams per linear inch across the grain, as explained hereinafter, the tissue paper is dried, treated to regenerate the cellulose, in the case of viscose, or to neutralize the alkali and harden the ether in the case of cellulose ethers deposited from alkaline solution, and finally dried at fixed dimensions under tension so that shrinkage of the tissue paper during the drying is inhibited. This paper possesses a residual shrinkage capacity which is expended when it is wet-out and finally dried in situ on the filamentary package, with shrinkage of the wrapper with the filamentary package.

The paper or base sheet comprises a thin tissue paper in which the fibers are bonded together by a bonding material to form a coherent but very flexible sheet. It

2,862,614 Patented Dec. 2, 1958 ICC outer peripheries of an annular package without injury to the wet gel filamentary material and without displacement of the surface windings or layers of the filamentary material. The base sheet comprises a thin tissue paper corresponding to a 5 pound to pound paper stock, that is, having a standard weight of from about 5 pounds to about 10 pounds. It is necessary to employ a tissue paper to provide a material which is air-permeable and liquid-permeable in order to allow the proper circulation of liquid through the package during normal aftertreatment and to permit escape of the water vapor during final drying of the wrapped package. The paper or base sheet must have a high tear resistance in the wet state and must have a wet strength of at least 300 grams per linear inch across the grain. A thin tissue paper having such minimum strength requirements and permeability requirements must have its fibers bonded together at their points of intersection as by regenerated cellulose, or by an alkali-soluble, water-insoluble cellulose ether, or by a resin such as a melamine-formaledhyde resin, or by a synthetic rubber such as neoprene added to the slush stock prior to sheeting of the paper-making fibers, or by autogenous bonding of conventional paper-making fibers and fibers of a potentially adhesive material which is rendered adhesive, for example, by heat, to bind the fibers in the sheet, and rendered non-adhesive by cooling. The base sheet comprising the paper-making fibers in the bonded condition also must have a wet strength such that it is capable of withstanding handling and processing in the normal treatment of acid-laden freshly formed regenerated cellulose yarns. The minimum Wet strength which the base sheet may have is 300 grams per linear inch across the grain, as determined by the following test:

A standard Suter tester having a loading rate of 4 grams per denier per second is equipped with gripping jaws. Strips of the base sheet 1 inch wide and'2 /2 inches long are immersed in water for at least 30 seconds and placed, while wet, between the jaws of the tester. The loading mechanism is then released so that the jaws move away from each other, exerting tension on the strip held between them. The tensile. strength is indicated automatically on'the gauge attached to the tester and is the weight in grams required to tear the strip.

The Suter tester is well known in industry and is generally used for measuring the tensile strength of yarns.

In the claims, when reference is made to a base sheet having a minimum wet strength of 300 grams per linear inch across the grain, the reference is to the strength as measured by the test described above.

According to one embodiment of'the invention, the base sheet is obtained by providing a tissue paper made from conventional paper-making fibers with a continuous thin coating of viscose having a low cellulose content, for example, a viscose containing from 0.6% to 0.9% of cellulose such as is obtained by diluting a normal viscose containing from 6% to 9% cellulose with water in the ratio of 9 parts water to 1 part viscose, and drying the coated paper to obtain a reinforced, high Wet strength tissue paper having a minimum'wet strength of 300 grams per linear inch across the grain, and the fibers of which'are bonded together by the viscose. This drying is preferably effected without any substantial regeneration of the cellulose, if the binder is viscose. though a continuous film is applied to the tissue paper, the cellulose concentration is sufliciently low so that upon drying of the coated sheet, thecellulose becomes concentrated on the fibers, particularly at the points of intersection of the fib'ers and thereby maintains the high porosity of 'the tissue paper.

A thicker viscose, for example, one containing from 1.5% tov 9% cellulose, and preferably from 6% to 9% cellulose, that is, a normal viscose as defined above or normal viscose which. has been diluted with from 1 to 3 parts of water per part of viscose, is superimposed on a surface of the base sheet in the form of parallel stripes and in an amount such that the final dried sheet has from 2% to 40% by weight of regenerated cellulose deposited on its surface in the form of the stripes. By final dried sheet is meant the sheet obtained after the treatment with sulfuric acid and drying of the sheet under tension. The viscose deposited on the base sheet of bonded paper-making fibers preferably has a ball fail viscosity of from 30 to 60v seconds, a sodium chloride salt test value of from 3 to 6, and contains from 6% to 9% of sodium hydroxide.

According to another embodiment, the fibersof the base sheet are bonded together by a water-insoluble, alkalisoluble cellulose ether, aqueous alkaline solutions, for example, sodium. hydroxide solutions containing from 0.5% to 3.0% of the ether being applied to the tissue paper for this purpose. The parallel stripes superimposed on the base sheet may also be stripes of a water-insoluble, alkalisoluble cellulose ether and for this latter purpose more concentrated solutions of the ether, for example, aqueous sodium hydroxide solutions containing from 3.5% to 8.0% of ether are useful.

The term water-insoluble, alkali-soluble cellulose ether is intended to include simple alkyl ethers, carboxyalkyl ethers, mixed alkyl hydroxyalkyl ethers, mixed alkyl carboxyalkyl ethers and the alkali metal salts of the carboxyalkyl ethers, which are insoluble in water but soluble in aqueous alkaline solutions of from 2 to 8% concentra tion at room temperature or at reduced temperature. These others are not dissolved by the aqueous media used in after-treating the regenerated cellulose filamentary material.

The proportion of binder in or onthe tissue paper necessary to give a base sheet of the required wet strength is low, and preferably the Weight of the paper-making fibers plus the weight of the binder is from about 0.5% to 2% greater than the Weight of the paper-making fibers. The weight of the base sheet, that is, the coherent structure comprising the paper-making fibers and the binder plus the superimposed stripes of regenerated cellulose or cellulose ether is preferably from at least 2.5% to not more than 42% greater than the weight of the sheet comprising the paper-making fibers only.

The superimposed stripes of regenerated cellulose or cellulose ether are preferably continuous, but they may be interrupted at spaced points around the outer periphery of the package, in use.

T1 e parallel stripes of regenerated cellulose or cellulose ether-superimposed onthe base sheet may have any width from about one-sixteenth inch to 2 inches and may be regularly or irregularly spaced apart a distance of from onc-fourth inch to 3 inches from edge to edge. The width of the stripes and the distance between them will be determined by the amount of regenerated cellulose or cellulose ether which it is desired to have present on the final dried paper sheet or wrapper. Wrappers having from 2% to of regenerated cellulose or cellulose ether superimposed on them in the form of spaced stripes are sufficiently porous to permit ready access of the treating liquids to the filamentary material and optimum shrinkage of the wrapper during the drying operation. The superimposed stripes which occupy at least and may occupy up to 40% of the area of the wrapper, not only cause the wrapper to shrink when it is dried on the package, but also reinforce the wrapper against tearing.

The condition of unbalance which exists as a result of the stripes of regenerated cellulose or cellulose ether superimposed on the surface of the permeable base sheet imparts a greater shrinkage to the wrapper per unit of weight increase than is obtained when the paper is provided with an overall coating of regenerated cellulose or cellulose ether of suflicient concentration to cause a strong shrinkage during drying. On the other hand, the base sheet must comprise fibers bonded together into a coherent structure by the binding material and the presence of a binder is indispensable.

Ordinary papers have a closely matted fibrous structure and have a low porosity. Although this class of paper may be of suflicient thinness to permit ready conforr ration of the paper to the inner and outer peripheries of an annular package, it is not satisfactory for the purposes of this invention. Such papers do not have a sufficient wet strength and the application of coatings or the inclusion of bonding materials as described hereinabove while increasing the wet strength sufilciently further reduce the porosity of the paper. The ordinary papers in themselves do not possess suflicient shrinkage nor do they possess a'sufficient porosity and permeability as required for the purposes of this invention. Superimposed stripes of viscose or the cellulose ether on the ordinary papers of sufiicient thinness do not provide the required shrinkage upon final drying because of the closely matted structure. Although the stripes might provide some shrinkage, even a small amount of shrinkage at the striped areas would result in a tearing of the intermediate areas because of the low Wet strength. It is essential, therefore, that a tissue paper which has a very open type structure be employed as the base sheet. The base sheet must possess a residual shrinkage and must have the high wet strength to allow the striped areas to shrink to a greater extent upon final drying without tearing at the intermediate areas. in tissue paper, there is a very open fibrous structure which accounts for the high porosity and permeability and viscose or a cellulose ether applied to paper is able to cause a high shrinkage in drawing the fibers together at the coated areas.

The sheet comprising the high wet strength tissue paper having the regenerated cellulose or cellulose ether stripes which is dried under tension shrinks at least 1% and preferably more when it is subsequently wet-out and dried relaxed as in the final drying of a filamentary package. The sheet material should have a shrinkage of about 5% or 6% to about 16% in the-direction across the grain and a shrinkage of about 3% or 4% to about 8% in the machine direction or in the direction of the grain. Preferably, the sheet material for wrapping of annular packages of filamentary material has a shrinkage of about 10% across the grain and about 5% in the direction of the grain.

The sheet comprising the regenerated cellulose or cellulose ether stripes has a minimum air-permeability of 117 cubic feet per minute per square foot of sheet, as determined by the standard air-permeability test (ASTM-D-737' 46) wherein air is drawn through the sheet and a pressure drop of about 0.5 inch of water is maintained between the opposite sides of the sheet.

In practicing the preferred embodiment of the invention, the stripes of viscose or alkali-soluble, water-insoluble cellulose ether are superimposed on the surface of the base sheet as a step in the manufacture of the paper. Thus, tissue paper sheeted from a pulp or stock comprising conventional paper-making fibers and having a Wet strength less than 300 grams per linear inch across the grain is passed through a bath comprising'the viscose of low cellulose content, or through the dilute aqueous alkaline solutionof the cellulose ether, whereby the fibers of the paper are bonded together to provide a base sheet which has a minimum wet strength of 300 grams per linear inch across the grain. The sheet is then passed over one or more drying cans or drums arranged in series as is common in the paper industry, and as it advances over the drying rolls, the thicker viscose or the more concentrated solution of the ether is deposited or applied in parallel stripes on a surface thereof. This may be accomplished by supporting a trough above one of the drying rolls and associating means with-the bottom wall of the trough for depositing the viscose or cellulose ether on the paper in stripes or, on one of the drying rolls, the paper may be contacted by an embossing or printing roll having parallel grooves in its surface and arranged to dip into the viscose or cellulose ether solution and then transfer the same to the-base sheet. The dried tissue paper having the spaced parallel stripes superimposed -on its surface is passed through'an'aqueous sulfuricacid solution, which may also oontainsodiurn sulfate and zinc sulfate, to regenerate the cellulose in the case of viscose or to neutralize the alkali in the case of the cellulose ethers. The paper is washed free of acid, 'an dried at fixed dimensions, under tension.

The dried tissue paper is then conformed .to the inner and outer peripheries of the filamentary package With the stripes of regenerated cellulose or cellulose ether extending circumferentially of the package, and the package is -subjected to the usual after-treating liquids, washed, and dried. During the drying, the regenerated cellulose or cellulose ether binder for the fibers, which occurs at all portions of the wrapper, shrinks causing shrinkage of the wrapper as a whole, while the superimposed stripes of regenerated cellulose or cellulose ether shrink more strongly, causing localized strong shrinkage of the wrapper. Because the stripes extend circumferentially of the package, those portions of the wrapper occupied by the stripes shrink with a draw-string effect, and the wrapper is pulled in against the package in the same manner as if it were tied on the package by a plurality of spaced bands. The result is an exceptionally neat package on which the wrapper does not slip in handling to disturb the windings, and which is ready to be shipped to the converter.

Instead of providing a tissue paper made wholly from paper-making fibers with a coating or binder of viscose or of a water-insoluble, alkali-soluble cellulose ether, to obtain a base sheet of the required minimum-wet strength, the base sheet may comprise fibers bonded together .by means of a resin, particularly a melamineformaldehyde resin, which is added to the beater of the paper-making machine in the form of the resin precondensate or applied to the tissue paper in the same manner as the viscose or cellulose ether, the precondensate being polymerized or fully condensed to insoluble, set condition during the drying operation. The base sheet may also comprise tissue paper obtained by adding 'a neoprene latex to the slush stock, the neoprene serving as a bonding agent for the fibers. Or the base sheet of minimum wet strength may comprise conventional paper-making fibers bonded together .by fibers of a potentially adhesive material activatable by heat to an adhesive condition in which they coalesce with the remaining fibers to bind the fibers in the sheet together and set in the bonded condition by cooling. The paper-making fibers and the bonding fibers may be mixed together in the beater of a conventional paper-making machine and sheeted in' the usual manner to form a tissue paper, the heating during drying of the sheet resulting in activation of the activatable fibers and bonding of the fibers in the sheet. The tissue paper may be perforated or non-perforated.

The wrapper made from the base sheet having regenerated cellulose or water-insoluble, alkali-soluble cellulose ether stripes or bands superimposed on a surface thereof may take the form of a seamless tube or cylinder, or of a tube or cylinder formed by overlapping'and sealing the edges in any appropriate manner, as by means of a there rnosensitive strip positioned therebetween and rendered adhesive by heating, or one surface of the sheet adjacent an edge thereof may be coated with an adhesive material I which binds the overlapped edges together. Alternatively, the tissue paper may be wrapped around the'fila-. mentarypackage and held thereon by merely allowing sufficient overlap.

Example I I A sheet of non-perforated tissue paper (8 pound stock) was passed through an aqueous medium obtained by diluting viscose containing 6% cellulose with 9 parts of water for each part of viscose. The coated sheet was dried to obtain a base sheet in which 'the fibers were bonded together into a coherent structure with the viscose, and having a minimum wet strength greater than 300 grams per linearinch across the grain. Viscose containing 7% cellulose was superimposed on a surface of the base sheet in the form of continuous, parallel stripes or bands one-eighth inch wide and regularly spaced apart a distance of 1 inch. The sheet was dried, passed through a cellulose-regenerating bath containing 10% sulfuric acid and 20% of sodium sulfate to regenerate the cellu-' lose from the viscose binder and from the superimposed viscose deposits, washed free of acid, and dried under tension. The regenerated cellulose stripes extended across the width of the tissue paper, as it was taken from lose regenerated from the superimposed viscose stripes shrank strongly in a draw-string effect so that the wrapper was drawn close to the package and conformed to its contours.

Example 11 A sheet ofnon-perforated tissue paper (8 pound stock) of wet strength less than 300 grams was passed through a 2% aqueous sodium hydroxide solution containing 1.5% of a hydroxyethyl cellulose containing an average of 0.10 ethylene oxide units per cellulose unit and having a standard viscosity of 0.25, and dried to obtain a base sheet having an across-the-grain wet strength of more than 300 grams. A 6% aqueous sodium hydroxide solution containing 8% of a hydroxyethyl cellulose containing an average of 0.36 ethylene oxide units per cellulose unit and having a standard viscosity of 6, was superimposed on the base sheet in the form of continuous parallel stripes one-eighth inch wide, the distance between the stripes being 1 inch. The ether was dried and the sheet was then passed through an aqueous solution of 1% sulfuric acid to neutralize the sodium hydroxide, washed free of acid, and dried under tension. The ether stripes extended across the width of the paper, as it left the drying zone. A cake of freshly prepared regenerated cellulose yarn was wrapped in the paper with the cellulose ether stripes extending circumferentially of the cake, and the wrapped cake was liquid-treated, washed and dried. The wrapper shrank with the cake during drying thereof .in the same manner as in Example I.

(NOTE-"@Thfi standard viscosity mentioned is the viscosity of-solutions containing water, 6% cellulose ether and 9% sodium hydroxide by weight measured at 25 C. and expressed as a multiple of the viscosity of glycerol, also measured at 25 C.)

Example III A paper stock was prepared by mixing a melamine formaldehyde resin precondensate with the pulp in the beater of a conventional paper-making machine. The stock was sheeted to obtain a tissue paper and dried; Viscose containing 9% cellulose was then deposited on the surface of the sheetand dried, 'togive a'basesheet; having parallel, continuous stripes; of viscose one-eighth inch wide and regularly spaced apart a distance of 1 inch superimposed thereon, and extending across the width of the paper. The paper was passed through an aqueous sulfuric acid solution to regenerate the cellulose, washed free of acid, and dried under tension. The paper, which had 7% of regenerated cellulose distributed in the striped condition on its surface, was used as a wrapper for a cake of freshly precipitated regenerated cellulose yarn, and

shrank with the cake when the wrapped cake was dried 4 after liquid-processing thereof.

Example IV A perforated tissue paper having a minimum wet strengthof more than 300 grams per linear inch across the grain was obtained by mixing a neoprene latex with the paper-making stock and sheeting the stock on a conventional paper-making machine. The sheet contained 0.5% of the neoprene. It was passed over the drying cans, perforated, and provided with continuous parallel stripes of viscose as in Example I. After processing as in Example I, the dried sheet was used as a wrapper for cakes of freshly prepared regenerated cellulose yarn. The sheet was placed on the cakes, with the regenerated cellulose stripes extending circumferentially of the cakes, and shrank during drying of the cakes after liquid-treatment thereof in the wrapped condition.

The invention includes wrappers formed from tissue paper, as well as those formed from tissue paper-like webs or matts of sufficient thinness and flexibility to be conformed generally to the peripheries of the package and having, prior to deposition of the viscose or cellulose ether stripes on the surface thereof, a minimum wet strength of 300 grams per linear inch across the grain. The wrapper may comprise thin webs or felt-iike structures obtained by associating two types of fibers at least some of which are potentially adhesive fibers, and activating the last-mentioned fibers to adhesive condition to bind fibers in the product. The term paper-making fibers is intended to include cellulosic fibers which willfibrill'atewhen beaten in a Water medium, for example, mechanical wood pulps, chemical wood pulps such'as those prepared by the sulphite process, sulphate or kraft process and the like, cotton fibers, fibers produced from rags, hemp fibers, either the crude or purified fibers, mixtures of fibers from these different sources, and the like.

This application is a continua-tiondn-part of copending applications Serial No. 138,064, filed January ll, 1950 entitled Shrinkable Wrappers for Annular Thread Pack.- ages and Serial No. 245,437, filed September 6, 1951 entitled Wrapper for Wound filamentary-Packages.

Since variations and modifications may be made in. practicing the invention without departing from the spirit and scope thereof, the invention is not to. be limited. except as defined in the appended claims.

We claim:

1. An assembly comprising an annular package of freshly prepared regenerated cellulose filamentary material and a shrinkable protective paper wrapper conformed to the contours of the package, the wrapper comprising a base sheet formed of a coherent, permeable tissue paper, the fibers of which are bonded toge'therat their points of intersection to provide a base sheet having a minimum wet strength of 300 grams per linear inchacross-the grain, and, superimposed on a surface of the base sheet, continuous, parallel stripes of a substance selected from the group consisting of regenerated cellulose-and alkali-solu ble, water-insoluble cellulose. ethers, the superimposed stripes constituting from 2% to 40% by weight of the wraper, the stripes having awidth of from one-sixteenth inch to two inches and spaced apart a distance of from, one to three inches from edge to edge and occupying at least 5% but not more than-40% of the area of the sheet and extending circumferentially' of-the wrapped package, the wrapper having a minimumair-perrr-ieability of about a 117 cubic feet per minute per square foot of area as determined by the ASTMD-737-46 air-permeability test 'wherein a pressure drop of about 0.5 inch of water is maintained betweenthe opposite sides of the wrapper and being characterized by having a greater shrinkability at the areas occupied by the superimposed stripes than at the uncoated areas.

2. An assembly comprising an after-treated, washed and dried shrunken package of regenerated cellulose filamentary material and a shrunken protective wrapper conforming closely to the contours of the shrunken package and formed of a coherent base sheet of liquid-permeable tissue paper the fibers of which are bonded together at their points of intersection to provide a base sheet having a minimum wet strength of at least 300 grams per linear inch across the grain, and, superimposed on a surface of the base sheet, continuous, parallel stripes of a substance selected from the group consisting of regenerated cellulose and alkali-soluble, water-insoluble cellulose ethers, the superimposed stripes constituting from 2% to 40% by weight of the wrapper, the stripes having a width of from one-sixteenth inch to two inches and spaced apart a distance of from one to three inches from edge to edge and occupying at least 5% but not more than 40% of the area of the wrapper and extending circumferentially of the wrapped package, the wrapper having a minimum air-permeability of about 117 cubic feet per minute per square foot of area as determined by the ASTMD737-46 air-permeability test wherein a pressure drop of about 0.5 inch of water is maintained between theopposite sides of the Wrapper and being further characterized by having the areas occupied by the stripes shrunken to a greater extent than the uncoated areas.

3. An assembly as defined in claim 2 wherein the wrapper comprises a coherent base sheet of liquid-permeable tissue paper the fibers of which are bonded together by a substance selected from the group consisting of regenerated cellulose and a water-insoluble, alkali-soluble cellulose ether.

4. An assembly as defined in claim 2 wherein the wrapper comprises a coherent base sheet of liquid-permeable tissue paper the fibers of which are bonded together by neoprene.

5. As an article of manufacture, a dry, shrinkable wrapper of sufficient thinness and flexibility to be conformed readily to both the inner and outer peripheries of an annular filamentary package and formed of a coherent base sheet of permeable tissue paper and tissue paper-like material, the fibers of the tissue paper and tissue paperlike material being bonded together at their points of intersection to provide a base sheet having a minimum wet strength of 300 grams per linear inch across the grain, and, superimposed on the base sheet, continuous, parallel stripes of a cellulosic material selected from the group consisting of regenerated cellulose and waterinsoluble, alkali-soluble cellulose ethers, the superimposed stripes constituting from 2% to 40% by weight of the wrapper, the stripes occupying at least 5% but not more than 40% of the area of the sheet, having a width of from one-sixteenth inch to two inches and being spaced apart a distance of from one-fourth inch to three inches from edge to edge, the wrapper having a minimum airpermeability of about 117 cubic feet per minute per square foot of'area as determined by the ASTMD737 46 air-permeability test wherein a pressure drop of about 0.5 inch of water is maintained between the opposite sides of the wrapper and being characterized by having a greater shrinkability at the areas occupied by the superimposed stripes than at the uncoated areas.

6. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 5 wherein the base sheet has, superimposed on a surface, continuous, parallel stripes of regenerated cellulose.

7. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 5 wherein the base sheet has,

superimposed on a surface, continuous, parallel stripes of a a water-insoluble, alkali-soluble cellulose ether.

8. As an article .of manufacture, a dry, shrinkable wrapper as defined in claim wherein the base sheet has, superimposed on a surface, continuous, parallel stripes of a water-insoluble, alkali-soluble hydroxyethyl cellulose.

9. As an article of manufacture, a dry, shrinkable wrapper of suflicient thinness and fiexibilityto be conformed readily to both the inner and outer peripheries of an annular filamentary package and formed of a coherent base sheet of permeable tissue paper, the of the tissue paper being bonded together at their points of intersection to provide a base sheet having a minimum wet strength of 300 grams per linear inch across the grain, and, superimposed on a surface of the base sheet, con tinuous, parallel stripes of a cellulosic material selected from the group consisting of regenerated cellulose and Water-insoluble, alkali-soluble cellulose ethers, the superimposed stripes constituting from 2% to 40% by weight of the wrapper, the stripes occupying at least 5% but not more than 40% of the area of the sheet, having a width of from one-sixteenth inch to two inches and being spaced apart a distance of from one to three inches from edge to edge, the wrapper having a minimum air-permeability of about 117 cubic feet per minute per square foot of area as determined by the ASTM-D-73746 air-permeability test wherein a pressure drop of about 0.5 inch of Water is maintained between the opposite sides of the wrapper and being characterized by having a greater shrinkability at the areas occupied by the superimposed stripes than at the uncoated areas.

10. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 9 wherein the fibers of the tissue paper are bonded together by regenerated cellulose and the base sheet has, superimposed on a surface,

continuous, parallel stripes of regenerated cellulose.

11. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 9 wherein the fibers of the tissue paper are bonded together by a water-insoluble, alkali-soluble cellulose ether and the base sheet has, superimposed on a surface, continuous, parallel stripes of regenerated cellulose.

12. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 9 wherein the fibers of the tissue paper are bonded together by a water-insoluble, alkali-soluble cellulose ether and the base sheet has, superimposed on a surface, continuous, parallel stripes of a water-insoluble, alkali-soluble cellulose ether.

13. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 9 wherein the fibers of the 5 tissue paper are bonded together by a melamine-formal- 10 dehyde resin and'the base sheet has, superimposed on a surface, continuous, parallel stripes of regenerated cellulose.

14. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 9 wherein the fibers of the tissue paper are bonded together by a synthetic rubber and the base sheet has, superimposed on a surface, continuous, parallel stripes of regenerated cellulose.

15. A dry shrinkable sheet comprising a base sheet formed of permeable tissue paper having a minimum wet strength of 300 grams per linear inch across the grain and of sufiicient thinness and flexibility to be conformed readily to both the inner and outer peripheries of an annular package, the base sheet having from 2% to 40% of a cellulosic material selected from the group consisting of regenerated cellulose and water-insoluble, alkalisoluble cellulose ethers superimposed on a surface of the base in the form of continuous parallel stripes which occupy at least 5% but not more than 40% of the area of the sheet, the stripes having a width of from one-sixteenth inch to two inches and being spaced apart a distance of from one to three inches from edge to edge, the sheet being characterized by having a greater shrinkability at the areas occupied by the stripes than at theuncoated areas.

16. A dried shrunken sheet comprising a base sheet formed of permeable tissue paper having a minimum wet strength of 300 grams per linear inch across the grain and of sufficient thinness and flexibility to be conformed readily to both the inner and the outer peripheries of an annular package, the base sheet having from 2% to 40% of a cellulosic material selected from the group consisting of regenerated cellulose and water-insoluble, alkalisoluble cellulose ethers superimposed on a surface of the base in the form of continuous parallel stripes which 0ccupy at least 5% but not more than 40% of the area of the sheet, the stripes having a width of from one-six teenth inch to two inches and being spaced apart a distance of from one to three inches from edge to edge, the wrapper being characterized by having the areas occupied by the stripes shrunken to a greater extent than the uncoated areas.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN ASSEMBLY COMPRISING AN ANNULAR PACKAGE OF FRESHLY PREPARED REGENERATED CELLULOSE FILAMENTARY MATERIAL AND A SHRINKABLE PROTECTIVE PAPER WRAPPER CONFORMED TO THE CONTOURS OF THE PACKAGE, THE WRAPPER COMPRISING A BASE SHEET FORMED OF A COHERENT, PERMEABLE TISSUE PAPER, THE FIBERS OF WHICH ARE BONDED TOGETHER AT THEIR POINTS OF INTERSECTION TO PROVIDE A BASE SHEET HAVING A MINIMUM WET STRENGTH OF 300 GRAMS PER LINERA INCH ACROSS THE GRAIN, AND, SUPERIMPOSED ON A SURFACE OF THE BASE SHEET, CONTINUOUS, PARALLEL STRIPES OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF REGENERATED CELLULOSE AND ALKALI-SOLUBLE, WATER-INSOLUBLE CELLULOSE ETHERS, THE SUPERIMPOSED STRIPES CONSTITUTING FROM 2% TO 40% BY WEIGHT OF THE WRAPER, THE STRIPES HAVING A WIDTH OF FROM ONE-SIXTEENTH INCH TO TWO INCHES AND SPACED APART A DISTANCE OF FROM ONE TO THREE INCHES FROM EDGE TO EDGE AND OCCUPYING AT LEAST 5% BUT NOT MORE THAN 40% OF THE ARE OF THE SHEET AND EXTENDING CIRCUMFERENTIALLY OF THE WRAPPED PACKAGE, THE WRAPPER HAVING A MINIMUM AIR-PERMEABILITY OF ABOUT 117 CUBIC FEET PER MINUTE PER SQUARE FOOT OF AREA AS DETERMINED BY THE ASTM-D-737-46 AIR-PERMEABILITY TEST WHEREIN A PRESSURE DROP OF ABOUT 0.5 INCH OF WATER IS MAINTAINED BETWEEN THE OPPOSITE SIDES OF THE WRAPPER AND BEING CHARACTERIZED BY HAVING A GREATER SHRINKABILITY AT THE AREAS OCCUPIED BY THE SUPERIMPOSED STRIPES THAN AT THE UNCOATED AREAS. 